Soil, Compost, and Liquid Sampling Instructions
Details how to take a soil, compost, or liquid samples and how much material is needed to perform the test(s).
For instructions on how to mail your samples for their safe arrival to our lab, click here.
Soil Testing Overview
We utilize a variety of testing methodologies to measure the abundance of life in soils and soil amendments. All testing methods are scientifically validated. Results provide indicators of soil health and function (references available upon request).
Testing packages and the individual assays are defined below. Except where noted, these tests do not identify specific organisms. These tests measure the Biomass of Total Populations in general categories of the functional groups. Totals of these groups represent a snapshot of the biological profile of the soil or amendment at the time of testing. While each of these tests can be performed singularly, together they represent a comprehensive picture of the health and utility of the material tested.
Measuring the Biomass of bacteria in a sample is the first step in understanding the health of a soil and the potential benefit of an inoculum or amendment. Total population of bacteria provides us with an indicator of abundance of food for predators, nutrient cycling capacity and general diversity of the bacterial population. We report this number as micrograms per gram or micrograms per milliliter (μg/g or μg/ml) of biomass. The Active population is the component of the Total Biomass that is currently metabolizing oxygen; i.e., the functional fraction of the bacteria. The relative range of these two numbers varies based on crop type and season. When looking at inoculants the balance between Active and Total is important for two different reasons: In compost this balance needs to be below 10%, indicating a mature and stable material. In liquid inoculums, higher ratios are better for a foliar application. This high activity assists the organisms stick to the plant surface. For soil application of a liquid, this balance may not be as critical as bacteria will become active in the soil environment.
Fungi play an important role in nutrient retention and transportation, soil structure and pH in the soil. Plant system succession is directly linked to the ratio of Fungi to Bacteria and is the first area we address when we approach remediation steps. Like bacteria, we report Biomass of Fungi in as micrograms per gram or micrograms per milliliter (μg/g or μg/ml). Instead of counting individual populations, we measure length and width of fungi present. Reporting this as biomass we can do direct comparisons of Fungi and Bacteria. When we observe and measure fungi we are looking at three primary things, total population, activity level (same basic method as Bacteria) and average hyphal diameter. Diameter not only helps us determine biomass, but in general terms, identifies whether the overall population of fungi is beneficial. On average diameter greater than 2.5 μm is ideal. Hyphal diameter also helps in reporting relative diversity; the more diverse the fungi present in the sample, the better.
Measuring Protozoa is a bit different from measuring Bacteria and Fungi. Our method involves creating several dilutions of the sample and then correlating presence and absence of each group to create a Most Probable Number #/g or #/ml. Unlike bacteria and fungi, it can take up to 5 days to complete this test. Protozoa are typically single cell organisms that feed upon bacteria. Flagellates and Amoebae are true aerobes, meaning they must have adequate oxygen to survive, while Ciliates are Facultative Anaerobes, meaning they can survive in low oxygen conditions. Numbers of Protozoa in are very important as an indicator of potential nutrient cycling. If there are sufficient levels of Flagellates and Amoebae then aerobic nutrient cycling can occur; however, high levels of Ciliates can be an indicator that anaerobic nutrient cycling is occurring. We use Ciliates to help identify potential anaerobic conditions in the sample.
The process for identifying and quantifying Nematodes is relatively simple in function, but the results are often a very useful indicator of the health of soil. Similar to Protozoa, Nematodes are very important for the nutrient cycling they provide. We report total number of Nematodes per gram or ml in the sample, then we breakdown this total population to Genus and Functional Group. The Functional Groups of Nematodes are: Bacterial Feeders: This group of Beneficial Nematodes feeds on bacteria, they help to keep the bacterial populations in balance and in the process of consumption cycle soluble nutrients in the root zone of the plants. Fungal Feeders: As the name would suggest this group of Nematodes feeds on fungi, again, keeping these populations in balance and cycling nutrients in the root zone. Many of these types of Nematodes also feed on fungi that can cause disease in plants. Having a good, diverse population of these organisms can be a valuable asset for plants that are more susceptible to some types of fungal diseases. Predatory Nematodes: These Nematodes are specialized in eating other Nematodes; typically they prey on Root Feeding Nematodes and can help minimize the damage from them. This group will also consume Protozoa and some types of micro‐arthropods. Again, their excretions become an excellent source of nutrients for plants. Fungal/Root Feeders: This is an interesting group of Nematodes, they typically act as Fungal Feeders, but if the population of Fungi is low, or if the right combination of plants and Nematodes are present they will eat the roots of the plants. We use this group as an indicator for both healthy fungal populations and, at the same time, for potential disease issues in the plants. Root Feeders: This is the group of Nematodes that is truly parasitic to plants. There are many types, and depending on the Genus and the plant being grown, they can be a real problem for production and plant health. As few as one root feeder per gram of soil can hinder productivity. As an indicator of soil health, this is a group to watch. By looking at the total population and functional groups of Nematodes in a soil or solid amendment such as compost, while cross‐referencing the plant being grown, we can get a fairly good picture of productivity. In solid amendments, we can find very high numbers of Nematodes, but usually very low diversity; however, despite the low diversity, compost is one of the best sources for nematode inoculants. In liquid amendments, such as compost tea, we typically find very few Nematodes; they do not like pure liquid environments.
This value is NOT a measurement of the chemical level of nitrogen in the sample, as most chemical soil tests show. Nitrogen cycling potential is a value directly correlated to the Protozoa and Nematode levels in the sample. Assuming these organisms survive and there is an adequate level of nitrogen, oxygen, and prey, this test result is the potential nitrogen (shown in pounds per acre) that is cycled by these organisms in a three to six month period. This value can be very useful in determining efficient application levels of nitrogen fertilizer.
Mycorrhizal Fungi are an important type of fungi that creates a symbiotic relationship with the root system of most plants, allowing for more nutrient and water uptake into the plant. We test for percentage (%) of colonization of three general types of these fungi, ENDO (inside the root) and ECTO (outside the root) and ERICOID (associated only with Ericaceous plants). Most plants require just one type, but a few types require both ENDO and ECTO. Ericoid mycorrhiza are associated with Ericaceous plants, such as Blueberries, Huckleberries and Rhododendrons. NOTE: You must include 10 inches (25 cm) root material in your sample in order for us to perform the Mycorrhizal Colonization test. It is also important for us to know the type of plant roots we are testing to be sure we look for the correct type of colonization.
This is currently the only test we perform for finding and enumerating a specific bacterial organism. We use a plate count method and report in colony forming units (CFU) per gram or milliliter of the sample. Our method is approved by the EPA for testing E. coli. The E. coli test is typically performed on soil amendments, such as compost or compost tea, to identify potential health risks. Each state has regulations regarding safe levels of this organism for use on food crops and for material handler safety.
This soil chemistry test uses a modified Spurway method that illustrates what nutrients are actually available to the plant in the root zone. It is not a measure based solely on extractable macro-nutrients as most other chemistry tests are. Our Crop Specific Nutrient Package gives you more information than many other chemistry tests as well, including the following assays: pH, soil type, Humus content, soluble salts, Calcium, Nitrates, Ammonium, Phosphate, Potassium, Magnesium, Iron, Manganese, Boron, Copper, Zinc, Sulfates and Chlorides. The information from this test correlates well to soil biology testing and gives you a complete picture of what is happening near your plant’s roots. This test can also be performed without a specific crop indicated to obtain an available nutrient “baseline” on soils, composts and liquid amendments such as compost tea.
International Soil Permit and Testing Form
To Our Valued International Customers:
Earthfort is pleased to offer testing to clients living and sampling in other countries. In order to keep this service available, you must comply with United States Department of Agriculture’s regulations.
Clients sending foreign samples MUST contact us to request an official PPQ Form 599 customs permit to be shipped to you, prior to taking samples and shipping them to us. Please call us at (541)257-2612 or email us at email@example.com for details. Click here to download a Foreign Testing Order Form. Earthfort’s form must be filled out and enclosed with your samples, but it is NOT a substitute for the official PPQ 599 customs permit!
UNDER NO CIRCUMSTANCES ARE YOU TO HAND CARRY ANY TYPE OF FOREIGN SAMPLE INTO THE UNITED STATES, SAMPLES MUST BE SHIPPED PER PERMIT REQUIREMENTS. Failing to follow USDA requirements for packaging and shipping of samples can result in delays in samples arriving at our lab, returned packages, and fines up to $300,000 US dollars, as well as our discontinuation of this service. These requirements are in place to safeguard United States agriculture and natural resources; violations of these regulations are taken very seriously.
Thank you for your business!
The Earthfort Team
IMPORTANT NOTE: Earthfort is pleased to offer testing to clients sampling soil and amendments in other countries. In order to keep this service available, you must comply with United States Department of Agriculture’s regulations. Clients sending foreign samples MUST contact us to request an official PPQ Form 599 Customs Permit to be sent to you, prior to taking samples and shipping them to us. UNDER NO CIRCUMSTANCES ARE YOU TO HAND CARRY ANY TYPE OF FOREIGN SAMPLE INTO THE UNITED STATES, SAMPLES MUST BE SHIPPED PER PERMIT REQUIREMENTS. Failing to follow USDA requirements for packaging and shipping of samples can result in delays in samples arriving at our lab and fines up to $300,000 US dollars, as well as our discontinuation of this service. These requirements are in place to safeguard United States agriculture and natural resources; violations of these regulations are taken very seriously.
Mailing Soil Within the United States and U.S. Territories
Mailing International Soils, Composts & Liquid Amendments
We’re here to help. Call (541)257-2612 or email us at firstname.lastname@example.org
If you measure your soil biology; you can manage it. Earthfort has measured soil biology across the world for over 20 years. Our proven methods of direct count microscopy are referenced below in Assay Descriptions.
Our Earthfort Essential Test measures the content and biology of soils and composts. It assesses moisture level, total and active bacteria, total and active fungi, and the presence of aerobic protozoa. We can also test for nematodes (identified to Genus), E. Coli, mycorrhizal colonization, and nitrogen cycling potential. Check out our Testing Order Form for details about each of our testing packages.
Upon receiving your test results, an Earthfort associate will provide a telephone report interpretation for those customers new to interpreting soil and compost data. If requested, we are able to provide remediation consulting for those who would like assistance on the practical application of soil amendments (fees may apply).